I know most of the people on here are from the south and don't know what cold is but since you guys know these trucks inside and out maybe you can help. I put LPP log tubes, ORY, and a Gibson Extreme Dual on my truck a couple months ago when it was warm out. I also cut the bottom of the airbox off, bypassed the cooling line going to the throttle body, and descreened the MAF. I don't know if it matters but I thought I should mention it.

I have been noticing my gas mileage getting worse and worse the last week as it gets colder and colder. Tonight when I was climbing a hill I noticed my gas gauge dropping and it didn't come back when i was on level ground. I have 500-600 pounds in the back of my truck. It was 9 degrees out when I did this, the truck was really loud and pulled hard.

Is the factory tune going nuts because of the headers and the cold? Is the truck running right? Any info would be appreciated.